Hard
If a : b = 2 : 3 and b : c = 4 : 5, then a : c is equal to:
Explanation
Explanation
Step 1: The value of b is different in the two ratios (3 and 4), so make it the same. The LCM of 3 and 4 is 12.
Step 2: Multiply the first ratio by 4: a : b = 8 : 12.
Step 3: Multiply the second ratio by 3: b : c = 12 : 15.
Step 4: Now b is 12 in both, so a : b : c = 8 : 12 : 15.
Step 5: Therefore a : c = 8 : 15.
Answer: 8 : 15.
PRO TIP
Re-check your working by substituting the answer back into the original question.